Chimoii
We removed all the velcro. At one time we removed half of the stock foam from the berth cushions and put memory foam to replace the half we removed. That was not the answer and so since we had zippers put on the factory cushions we switched the foam back to all the factory stuff. Then we made up a topper with 4" memory foam egg crate type, still not happy, as this slid around and did not hold the cushions in place very well. So we added a second piece of 4" memory foam with the egg crate sides facing each other and that was the answer. We had a professional canvas guy make the bag with a non slip material on the bottom and Sunbrella on the top. The non slip surface of the new berth shaped bag keeps the Cushions from moving. No need anymore for the velcro. So we have the original factory cushions with their standard foam; the two pieces of 4" memory foam with the egg crate side facing each other so it's only about 5" thick in a non slip bottomed berth shaped bag. A berth shaped sleeping bag system called a TravaSak sits on top of that. We just sleep on top of everything and have a queen sized medium weight comforter to cover us up. We spend up to 30 days on the boat at a time and sleeping in the berth is never a problem. It took us a while of trail and error but this works great for us.
D.D.